1. Technical Field
The present invention relates to a network system and a method of controlling the same. More particularly, the invention relates to a network system, and a method of controlling the same, wherein variable Internet protocol (IP) addresses of network units are viewed as fixed IP addresses.
2. Related Art
All network units (for example, host computers, routers, set-top boxes, etc.) connected to the Internet generally have unique transmission control protocol/Internet protocol (TCP/IP) addresses which enable the corresponding network units to access other network units located in all parts of the world so as to utilize Internet services.
The TCP/IP is an aggregate of two protocols, a transmission control protocol and an Internet protocol, and supports the exchange of data between different network units. Software modules employing the TCP/IP are required for the connection of network units to the Internet. These software modules may be, for example, Internet Explorer, Netscape, etc. The TCP/IP is currently adopted as a standard protocol of the Internet, and its address, or IP address, is typically composed of four parts, each being a numeral (for example, 211.203.81.245), for identifying a corresponding communication network or network unit. Different Internet IP addresses are assigned to network units connected to the Internet throughout the world, and are managed by a network information center (NIC).
Such IP addresses of network units may generally be classified into two types: a fixed IP address and a variable IP address. The fixed IP address, owing to its unchangeability, is preferred to enable a user to access a corresponding network unit by entering it at any place, but it is disadvantageous in that an operator of the network unit has to pay an IP company a high rate for using it.
As compared with the fixed IP address, the variable IP address is assigned by a dynamic host configuration protocol (DHCP) server in such a manner that it is permitted to be used only for a predetermined period of time. In this regard, a network unit employing such a variable IP address must be again assigned a valid IP address from the DHCP server after the predetermined period of time elapses. This variable IP address is disadvantageous in that it is variable, but it has the advantage that an operator of the network unit can utilize the Internet at a lower rate as compared to the higher rate of the fixed IP address.
If a network unit employs a variable IP address, a user will have to recognize the variable IP address to gain access to the network unit. However, the user has no way of recognizing the variable IP address because the DHCP server selects any one of numerous valid IP addresses held therein randomly as the variable IP address, and then assigns it to the network unit. As a result, the user cannot access the network unit because he or she cannot recognize the variable IP address. Consequently, an operator of the network unit is obliged to employ the high-cost fixed IP address.
The following are considered to be generally relevant to the present invention but are burdened by the disadvantages set forth above: Korean Patent Publication No. 12264/2000 to Byung-Jin Lim, entitled SERVER CONNECTING METHOD AND SYSTEM FOR DYNAMIC IP ADDRESS, published on Mar. 6, 2000, Korean Patent Publication No. 41829/2000 to Sun-Hui Kim et al., entitled PRIVATE IP ADDRESS OPERATING APPARATUS IN MULTI-MEDIA SATELLITE TELECOMMUNICATION SYSTEM, published on Jul. 15, 2000, U.S. Pat. No. 6,012,088 to Li et al., entitled AUTOMATIC CONFIGURATION FOR INTERNET ACCESS DEVICE, issued on Jan. 4, 2000, U.S. Pat. No. 6,052,725 to McCann et al., entitled NON-LOCAL DYNAMIC INTERNET PROTOCOL ADDRESSING SYSTEM AND METHOD, issued on Apr. 18, 2000, and U.S. Pat. No. 6,128,664 to Yanagidate et al., entitled ADDRESS-TRANSLATING CONNECTION DEVICE, issued on Oct. 3, 2000.